I'm guessing you created a new mod and are trying to add HL2 content to it ? if that is the case in hammer you need to go to tools>options and select your mod's configuration then under "Game Data files" hit add and select "halflife2.fgd" then you should get a nice long list of entities that you can add, as long as you made a single player mod you should be fine. Another suggestion is you might want to create a custom FGD for your mod, and add that one, as long as it is added after the base.fgd you shouldn't get any errors about missing base types. That way you can have all your entity entries separate from the base.
Thanks guys, thanks Cunbelin that is exactly what I have done>created a single player mod. I'll try that tonight! Will It give me a list of npc entities when done?
ok the only way I could get HL2 entities to apear in my mod was to type them in manually into the Entity name listbox. Doing it this way however gives me an "obsolete entity/jackie chan' Icon and no options. It DOES work once in game however, but at the cost of arkwardness.
I tired Cunbelin's advice of adding the Halflife2.fgd file to the hammer options, but it seems to have no effect when im in my mod.